Proposal of 1-cell reuse OFDM/TDMA using subcarrier adaptive modulation and multilevel transmit power control for broadband wireless communication systems

This paper proposes a 1-cell reuse OFDM/TDMA system that employs subcarrier adaptive modulation scheme (AMS), total-and multilevel (subcarrier) transmit power control (TPC, MTPC) schemes to achieve broadband wireless communication systems. In the proposed system, because AMS and MTPC are operated according to the predicted signal to interference plus noise power ratio (SINR), suppression of rapid change of both the desired and interference signal level is a key for higher throughput. Hence, we employ diversity reception and discuss its impact on suppression of dynamic range and variation speed of interference signal level in addition to the desired signal level. Moreover, in order to avoid stepwise changes in interference level due to the modulation level change in AMS process, we optimize averaging period of interference level used in AMS and MTPC processes, and the update rate for subcarrier TPC and modulation level control. Computer simulation confirms the proposed system with optimized parameters achieves equivalent cell reuse factor of 1.57 under 3-sector cell configuration.